This invention relates to anti terrorist barricades capable of stopping the movement of vehicles unauthorized to enter a trafficway. A vehicle moving toward such a barricade has a certain kinetic energy which is a measure of the hitting power it possesses. This kinetic energy is calculated from the vehicle weight and velocity, and on impact with such a barrier the kinetic energy is then converted into heat, sound and deformation of the vehicle, and in some cases deformation of the barrier, in this case the "bollard". In actual practice, the total energy dissipation depends upon varying factors prevailing at the moment of impact, all of which need not be detailed here. However for example, a vehicle moving at 50 mph has twenty times as much kinetic energy as it would moving at 10 mph; or for example an armored car weighing thirty times as much as a small passenger car and moving at 10 mph would have less kinetic energy than said passenger car moving at 60 mph. It is within this approximate range of kinetic energy with which this invention is primarily concerned, it being a general object of this invention to provide a retractile bollard that is configured to provide maximum protection against vehicle assault within a minimum package or installation area. Multiple bollards are to be used to barracade a trafficway.
In accordance with this invention, the bollard is a structural steel fabrication that is instantaneously lifted into working position by a directly coupled spring means, so that it can be extended as a barrier to traffic. The bollard and spring means is depressed during the interim time awaiting release for extension. The geometry of the bollard is disposed and rotatably oriented so that the energy of impact is efficiently transmitted into a rugged foundation that absorbs said energy, within its elastic limit that exceeds the rupture point of the bollard under the same impact conditions. Accordingly, under major impact conditions the bollard per se may be damaged or destroyed and it is therefore considered to be expendable and adapted to be readily replaced. It is an object of this invention, therefore, to provide a barrier of unit construction wherein the bollard is individually replaceable.
The retractile bollard of the present invention is characterized by the aforesaid foundation and by a direct installation of the bollard in said foundation. A feature is the flush trafficway condition of this barrier unit, when the bollard is retracted, and to this end access means as disclosed herein provides for disassembly and repair, service and replacement of the bollard per se. It is an object of this invention to provide for this accessability and replaceability.
The bollard is operated by a yieldable lift means, preferably by potential energy stored in a spring system as herein described. However, the term "lift means" or "spring" is to include such means as metal springs, elastic springs, pneumatic springs and hydraulic springs, and any other such resilient means or the like. In practice, operation is from a resilient metal coil spring, preferably a compression spring, as will be described. A feature of this barrier system is its capability of released by either manual or automatic remote operation, as circumstances require.
The typical collision point above grade is presumed to be approximately 17 inches, the average height of a vehicle bumper. Accordingly, the bollard is extended well above the point of collision, for example to a height of about two or three feet, all of which may vary as required. The actuation of the bollard between the vertically extended and the retracted position is manual through the application of a person's body weight for the storage of potential energy in the spring, it being an object to eliminate the necessity of power means heretofore required to raise such bollards. With the preferred form of bollard motivation, for extension, a manually depressible compression spring is employed, wherein potential energy is stored and available for subsequent instantaneous action. As disclosed herein, there is a latch that is manually controlled or automatically controlled as may be required. Lifting of the bollard is by the relase of potential energy stored in a spring and released as kinetic energy for instantaneous raising of the bollard.
A feature of this barrier unit installation is that it is self bailing and rids itself of the accumulation of surface waters. By cycling the bollard downwardly, most of the surface water entering into the foundation cavity can be pumped out.
Upon severe impact of a vehicle against a bollard type barrier, there is a tendancy for parts of the vehicle to move vertically as a result of forces imposed by the inertia of other collapsing vehicle parts. Upward vertical movement is to be avoided, it being an object of this invention to capture the vehicle against upward movement upon impact with the bollard. In practice, a lip is provided at the top of the bollard, and the lip being flush with the grade level when the bollard is retracted, and the lip being exposed to impacted vehicle parts when the bollard is extended.
Captured tamper-proof assembly of the bollard within the foundation therefor is essential, it being an object of this invention to provide retractile bolts in the foundation for working engagement with stops on the bollard, while limiting extension of the bollard with the guides means thereof engaged in the foundation.